Etfe lining member

ABSTRACT

The present invention provides a lining member in which an ETFE is used and which shows good adhesion and can show a reduction in coating film defects. An ETFE-lining member comprising a substrate, a primer layer and a surface layer laminated in this order, wherein said substrate comprises a metal or a ceramic, said primer layer comprises an ETFE (A) and a binder component, and said surface layer comprises an ETFE (B) having fluorine content higher than that of the ETFE (A).

TECHNICAL FIELD

The present invention relates to a lining member in which anethylene/tetrafluoroethylene-based copolymer is used and which is highin adhesion strength and has few coating film defects.

BACKGROUND ART

Apparatus for chemical or medical use and piping materials insemiconductor manufacturing plants, among others, are generallycontacted to chemicals and the like on the occasion of use thereof and,therefore, are desired to be resistant to chemicals and the like and tocorrosion. When the substrates constituting such apparatus, pipingmaterials and so forth are protected by a corrosion-resistant lining,for instance, they can be provided with corrosion resistance.

Among the lining members each provided with a lining, there are ones inwhich fluororesins, in particular ethylene/tetrafluoroethylenecopolymers [ETFEs], are utilized since they are easier to handle ascompared with the conventional glass linings and have good resistance tochemicals such as acids, alkalis, oxidizing and reducing agents andvarious solvents.

When used for lining members, ETFEs are applied generally in the form ofcoatings such as powder coatings and, in this case, primers to beapplied beforehand, as undercoats, to substrates are generally regardedas unnecessary, hence are not used. ETFEs are now in wide use in view ofsuch simplicity in using them.

ETFE-based coatings comprising an ETFE are applied to articles to becoated and then baked for forming s coating film. Generally, theresulting films are desired to have a certain thickness in terms ofbeing provided with corrosion resistance. In electrostatic coatingprocesses, for instance, the steps of application and baking at a hightemperature are repeated several times.

While ETFEs are by nature excellent in chemical resistance, amongothers, they are poor in adhesion to substrates and, therefore, whenthey are applied in the form of coatings to give relatively thick films,there arises a problem that the coatings may develop coating filmdefects such as cracks.

The formation of cracks results in a decrease in corrosion resistance.For avoiding cracking, it is impossible to increase the film thickness,hence the corrosion resistance has to remain poor. Thus, any ETFE-liningmember satisfactory in corrosion resistance has not been obtained asyet.

Although ETFEs are excellent in heat resistance and show a certaindegree of adhesiveness just after application thereof as coatings, theiradhesiveness decreases under severe conditions, such as hot water orhigh temperature conditions, to cause problems, namely coating filmdefects, such as cracks in coating films and peeling of f from articlescoated therewith.

ETFE-based coatings are sometimes applied to articles to be coated,which comprise chromium-containing metals such as stainless steels.Since chromium-containing metals promote the decomposition of ETFEs,there are problems on the application of the coating to articles to becoated.

To solve such problems and effectively use ETFE-based coatings, primerdevelopment has become desired. As a primer for ETFE-based coatings,there are known PPS-based primers comprising polyphenylene sulfide [PPS]and a polyamideimide resin.

However, no solvent is available for dissolving such PPS-based primers,hence these occur as solids. It is difficult to apply them onto articlesto be coated evenly and uniformly and, as a result, voids between theprimer and the substrate are readily occurred, resulting in peeling.Thus, they are incapable of completely solving the insufficient adhesionand coating film defect problems mentioned above.

ETFEs are generally high in alternating-copolymer character, the moleratio between ethylene and tetrafluoroethylne is 1:1, and the fluorinecontent is 59.4% by mass. However, ETFEs higher in fluorine content forimproving in gloss, transparency and flame retardancy have been desiredfor recent years. When the fluorine content is high, the adhesion tosubstrates is weak and, accordingly, coating film defects tend toappear. The demand for improvement in adhesion is thus increasing.

SUMMARY OF THE INVENTION

In view of the above-discussed state of the art, it is an object of thepresent invention to provide a lining member in which an ETFE is usedand which shows good adhesion and can show a reduction in coating filmdefects.

The present invention provides an ETFE-lining member comprising asubstrate, a primer layer and a surface layer laminated in this order,wherein said substrate comprises a metal or a ceramic, said primer layercomprises an ETFE (A) and a binder component, and said surface layercomprises an ETFE (B) having fluorine content higher than that of theETFE (A).

DETAILED DISCLOSURE OF THE INVENTION

In the following, the present invention is described in detail.

The ETFE-lining member comprises a substrate, a primer layer and asurface layer laminated in this order.

The above primer layer comprises an ETFE (A) and a binder component.

The primer layer is a coating film formed by applying a primer composedof the ETFE (A) and the binder component to the substrate, followed bydrying.

In the above primer, the ETFE (A) contained in the primer differs insurface tension from the binder component and, therefore, the ETFE (A)rises toward the surface in the step of baking for surface layerformation, which is to be described later herein, so that the ETFE (A)is disposed mainly on the surface side remote from the substrate,showing good adhesion to the surface layer comprising ETFE (B) owing tothe compatibility therebetween, while the binder component is disposedmainly on the substrate side, so that it can show good adhesion to thesubstrate.

In this specification, the term “ETFE (A)” means a copolymer obtained bypolymerizing mainly ethylene and tetrafluoroethylene and intended forincorporation in the above-mentioned primer. In this specification, acopolymer obtained by polymerizing mainly ethylene andtetrafluoroethylene is sometimes referred to also as “ETFE-basedcopolymer”. The ETFE-based copolymer may be a copolymer obtained bypolymerizing ethylene and tetrafluoroethylene alone or a copolymerobtained by polymerizing ethylene and tetrafluoroethylene plus a smallproportion of another monomer.

Preferably, the ETFE (A) is a product obtained by copolymerization ofethylene and tetrafluoroethylene, together with otherfluorine-containing monomers for the purpose of crystallinitycontrolling. The other fluorine-containing monomers as mentioned aboveare not particularly restricted but may be any of those capable ofadding to both of ethylene and tetrafluoroethylene. Fluorine-containingvinyl monomers containing 3 to 8 carbon atoms, such ashexafluoroisobutylene and CH₂=CFC₃F₆H, are easy to use. The otherfluorine-containing monomers as mentioned above preferably amount to notmore than 5 mole percent relative to all the monomers constituting theETFE (A) so that they may not impair the chemical resistance and heatresistance, among others.

The ETFE (A) preferably has a fluorine content of not lower than 50% bymass. As levels less than 50% by mass, deteriorations in heat resistanceand chemical resistance will result. The fluorine content of the ETFE(A) may be not more than 70% by mass if it is within the above range. Amore preferred lower limit thereto is 60% by mass. The ETFE (A) can havea fluorine content within the above range as a result of appropriateadjustment of the proportions of ethylene, tetrafluoroethylene and theother monomers to be used when desired. The fluorine content referred toabove is the value obtained by burning the fluororesin, causing thefluorine contained therein to be absorbed in an aqueous solution of analkali or the like and assaying the same by ion chromatography, forinstance.

Preferably, the ETFE (A) has a melt flow rate [MFR] of 0.1 to 100 g/10minutes. When the MFR is within the above range, the meltability of theETFE (A) becomes adequate for improving the adhesion thereof to theabove-mentioned surface layer. When the MFR is less than 0.1 g/10minutes, the adhesion between the primer layer and the surface layertends to decrease and, at levels exceeding 100 g/10 minutes, crackingdue to stress or stress cracking will easily occur, possibly leading todeterioration in corrosion resistance. Amore preferred lower limit is0.5 g/10 minutes, and a more preferred upper limit is 50 g/10 minutes.In this specification, the “MFR” referred to above is the value obtainedby carrying out measurements under a load of 5 kg at 297° C. accordingto ASTM D 3159.

Preferred as the above ETFE (A) is one having an average particle sizeof 0.1 to 30 μm. When the size is smaller than 0.1 μm, the primer layertends to undergo cracking, hence the film thickness tends to be thin andrestricted. When it exceeds 30 μm, no uniformity of dispersion will beattained, hence the adhesion to the surface layer will become uneven,resulting in poor adhesion. A more preferred lower limit is 0.2 μm, anda more preferred upper limit is 25 μm. A still more preferred lowerlimit is 0.5 μm, and a still more preferred upper limit is 20 μm. Inthis specification, the average particle diameter is the value obtainedby carrying out measurements using a laser diffraction/scattering typeparticle size measuring apparatus.

The ETFE (A) is obtained by polymerization using any of thepolymerization methods known in the art, for example the emulsionpolymerization technique. If desired, the ETFE powder obtained bypolymerization is pulverized so as to have an average particle diameterwithin the range mentioned above. The method of pulverization is notparticularly restricted but any of the methods known in the art, forexample the method disclosed in Japanese Kokai PublicationSho-63-270740, can be used. Thus, there may be mentioned, for example,the method comprising compressing the ETFE powder to a sheet-like formby means of a roll, followed by pulverization by means of a pulverizerfor classification.

The above-mentioned primer layer comprises a binder component inaddition to the above ETFE (A). The binder component is a componentcapable of functioning as a binder in the formation of the primer layerand it is preferably a heat-resistant resin since such resin can resistbaking temperatures for forming the surface layer to be described laterherein. In this specification, the term “heat resistant” means theproperty that enables continuous use at temperatures not lower than 150°C.

The heat-resistant resin is preferably a solvent-soluble resin capableof being dissolved in a solvent. The solvent-soluble resin is importantin being dissolved in a solvent and spreading as the binder componentall over the substrate surface for improving adhesion. Thesolvent-soluble resin is not particularly restricted but more preferablyis a polyamideimide resin, a polyethersulfone and/or a polyimide resin.These may be used singly or in combination of two or more species. Stillmore preferred from the adhesion viewpoint is a nitrogen atom-containingresin such as a polyamideimide resin or a polyimide resin.

The solvent capable of making the above solvent-soluble resin dissolvedtherein is not particularly restricted but one having a boiling point ofnot lower than 100° C. is preferred because of the ease of evaporationin the step of drying following primer application as described laterherein. As such solvent, there may be mentioned N-methyl-2-pyrrolidone,N,N-dimethylacetamide and N,N-dimethylformamide, among others.

The solvent for making the solvent-soluble resin dissolved therein ispreferably contained in an amount not less than 10% by mass of thesolvent-soluble resin on the solid matter mass basis. In levels lessthan 10% by mass, it is impossible to spread the solvent-soluble resinall over the substrate, therefore the adhesion is likely to bedeficient. A content of not less than 50% by mass is more preferred. Asthe amount of the solvent increases, the adhesion to the substrate tendsto improve.

The ETFE (A) preferably amounts to 50 to 90% relative to the sum of theETFE (A) and binder component. At levels lower than 50%, interlayerpeeling tends to occur between the resulting primer layer and thesurface layer and, at levels exceeding 90%, the content of the bindercomponent becomes too low and the adhesion of the resulting primer layerto the substrate will deteriorate. A more preferred lower limit is 60%,and a more preferred upper limit is 80%.

In this specification, the term “solid matter mass basis” means thatcalculations are made based on the dry solid matter. Therefore, as forthe ETFE (A), for instance, the mass percentage thereof on the solidmatter basis is 50 to 90% of the sum of the mass of the solid matter ofthe ETFE (A) and the mass of the solid matter of the binder component.

Thus, preferably, the ETFE (A) amounts to 50 to 90% of the sum of theETFE (A) and the binder component on the solid matter mass basis and theETFE (A) has a fluorine content of not lower than 50% by mass. TheETFE-lining member of the present invention can be obtained as one whoseprimer layer has good adhesion to both the substrate and the surfacelayer by using such ETFE (A).

The primer for obtaining the primer layer may comprise a heatstabilizer. By adding a heat stabilizer, it becomes possible to preventa resin such as the ETFE (A) from undergoing oxidation and other thermaldegradation in the step of baking for surface layer formation asdescribed later herein; as a result, the stability of interlayeradhesion of the resulting primer layer to the substrate and to thesurface layer can be improved.

The heat stabilizer is not particularly restricted but preferably is ametal oxide, an amine type antioxidant and/or an organic sulfurcompound.

The metal oxide is not particularly restricted but includes, amongothers, oxides of Cu, Al, Fe, Co, and Zn.

The amine type antioxidant is preferably an aromatic amine sincestability at high temperatures not lower than 250° C. is required. Thearomatic amine is not particularly restricted but preferably is a phenyland/or naphthyl group-containing amine derivative, in terms of excellentheat resistance. As such amine derivative, there may be mentioned, forexample, dinaphthylamine, phenyl-α-naphthylamine,phenyl-β-naphthylamine, diphenyl-β-phenylenediamine, andphenylcyclohexyl-β-phenylenediamine.

The organic sulfur compound is not particularly restricted but includes,among others, mercaptobenzimidazole compounds, mercaptobenzothiazolecompounds and thiocarbamic acids and salts thereof, and thiurammonosulfides. The above-mentioned salts are not particularly restrictedbut include salts with Zn, Sn, Cd, Cr, Fe and the like.

The heat stabilizer may be used by singly or in combination of two ormore species.

When to be used in the pharmaceutical, semiconductor or like field wherethe elution of metal ions is undesirable, in particular, the heatstabilizer is preferably a nonmetal compound leaving no residue,including amine type antioxidants and organic sulfur compounds otherthan metal salts.

The heat stabilizer is preferably used in an amount of 0.001 to 5% onthe mass basis relative to the solid matter content of the ETFE (A). Atlevels below 0.001%, the thermal stabilization effect may beunsatisfactory in some instances and, at levels exceeding 5%, theinfluence of foaming resulting from decomposition of the heat stabilizerbecomes great, resulting in poor adhesion in certain instances. A morepreferred lower limit is 0.003%, and a more preferred upper limit is 2%.

The primer layer and/or primer mentioned above may comprise an additive,according to need, in combination with the components mentioned above.The additive is not particularly restricted but includes those generallyused in primers for coating, for instance. Thus, it may be a pigment.The pigment is not particularly restricted but includes, among others,color pigments such as carbon, titanium oxide, red iron oxide and mica,rust preventive pigments, and calcined pigments.

Preferably, the primer further contains a dispersion medium. When thebinder component and ETFE (A) are dispersed as dispersoids in thedispersion medium mentioned above to give a disperse system(dispersion), the primer can be spread all over the substrate. When thebinder component is a soluble resin soluble in a solvent, thesolvent-soluble resin dissolved in the solvent constitutes thedispersoid.

The dispersion medium is not particularly restricted but includes, amongothers, water, alcohols, ketones, esters, and aromatic hydrocarbons.These may be used singly or in combination of two or more species. Amongthem, water is preferred from the working environment viewpoint.

When water is used as the dispersion medium, a surfactant is requiredfor dispersing the ETFE (A). The surfactant is not particularlyrestricted but includes, for example, nonionic, anionic and cationicsurfactants. It may be used singly or in combination of two or morespecies. The surfactant is preferably one capable of evaporating ordecomposing at relatively low temperatures around 250° C. A rustpreventive is preferably incorporated, when water is used as thedispersion medium or for the substrate may be prevented from beingcorroded on the occasion of coating. The rust preventive is notparticularly restricted but may be dibutylamine, for instance.

When water is employed as the dispersion medium, the ETFE (A) obtainedby emulsion polymerization may be used in a dispersion form withoutisolating the resin component. In this case, the water used in emulsionpolymerization may be used as the above dispersion medium, or water maybe further added, or the surfactant used in emulsion polymerization maybe used as such, or a surfactant may be further added. When the ETFE (A)is obtained by suspension polymerization as well, the solvent used insuspension polymerization may be used as the above dispersion mediumprovided that it falls within the above-mentioned range of dispersionmedium.

The primer can be prepared by any of the methods known in the art, forinstance. Thus, it can be prepared in the form of a coating byincorporating the pigment, viscosity modifier, film-forming material,solvent and so forth. After dispersion of these materials in optionalproportions, the coating may be adjusted to a viscosity facilitatingapplication thereof with a viscosity modifier or the like.

The pigment is used in a form pulverized and dispersed in apulverizer/disperser, such as a basket mill, dynamo mill or ball mill,together with the above-mentioned water, binder component, surfactant,etc.

When it is of a dispersion type, the ETFE (A) has a relatively smallaverage particle diameter of about 0.5 μm and, therefore, can bedispersed as such in the above-mentioned primer. As the dispersion typeETFE (A), use is generally made of one produced by emulsionpolymerization and concentrated with the surfactant mentioned above.When the ETFE (A) is used in a powder form with an average particlediameter of 1 to 30 μm, the powder is wetted with the dispersion mediumby using the above surfactant and then mixed with the binder component.

When water is used as the dispersion medium, the same or nearly the samevolume of the binder component as that of the pigment is used andpulverized and dispersed beforehand in water, followed by mixing up withthe other components of the primer. The heat stabilizer mentioned aboveis preferably added on the occasion of pigment pulverization because ofthe convenience from the production viewpoint.

The surface layer comprises the ETFE (B).

The surface layer is a coating film formed by applying a coating forsurface layers comprised of the ETFE (B) onto the primer layer, followedby drying, if necessary, and by baking.

In this specification, the term “ETFE (B)” means a copolymer obtained bypolymerizing ethylene and tetrafluoroethylene as main comonomers andintended to be incorporated in the coating for surface layers. The ETFE(B) is thus conceptually distinguished from the ETFE (A), which isincorporated in the primer, in that it is incorporated in the coatingfor surface layers.

The ETFE (B) has a fluorine content not lower than the fluorine contentof the ETFE (A). In this specification, that “the ETFE (B) has afluorine content not lower than the fluorine content of the ETFE (A)”means that the fluorine content value (b) of the ETFE (B) to be used isequal to or greater than the fluorine content value (a) of the ETFE (A)to be used. Thus, that “the ETFE (B) has a fluorine content not lowerthan the fluorine content of the ETFE (A)” refers to the case ofcomparing the fluorine contents of a copolymer actually employed in theETFE-lining member of the present invention between copolymers belongingto the category of “ETFE (B)” and copolymers belonging to the categoryof “ETFE (A)”.

As mentioned hereinabove, the ETFE (A) preferably has a fluorine contentof not lower than 50% by mass, and the fluorine content may be nothigher than 70% by mass provided that it is within the above range,while, as described later herein, the ETFE (B) preferably has a fluorinecontent of 50 to 70% by mass. Therefore, the respective preferredfluorine content ranges of ETFE (A) and ETFE (B) may be said to coincidewith each other. The fluorine contents of the copolymers actually usedin the ETFE-lining member of the present invention are desirably withinthose preferred ranges in ETFE (A) and ETFE (B) respectively and namelythe above-defined (a) and (b), the fluorine contents of the copolymersactually used satisfy the relation (a)≦(b).

Owing to the use of the ETFE (A) and ETFE (B) having such respectivefluorine contents, the ETFE-lining member of the present invention canbe obtained as one excellent in interlayer adhesion between the primerlayer and the surface layer. If the fluorine content of the ETFE (B) islower in value than the fluorine content of the ETFE (A), the interlayeradhesion between the primer layer and, due to surface tension, thesurface layer will be low, resulting in coating film defects; this isunfavorable.

The ETFE (B) preferably has a fluorine content of 50 to 70% by mass.When the ETFE (B) to be used in the surface layer has a fluorine contentwithin the above range, the ETFE-lining member of the present inventioncan be obtained as one not only improved in corrosion resistance, flameretardancy and other surface characteristics but only excellent inappearance. From the corrosion resistance viewpoint, amore preferredlower limit to the fluorine content of the ETFE (B) is 60% by mass and,from the gloss, transparency and flame retardancy viewpoint, a stillmore preferred lower limit thereto is 62% by mass and a more preferredupper limit is 68% by mass. When the fluorine content of the ETFE (B) iswithin the above range, the ETFE-lining member of the present inventioncan show the above-mentioned excellent surface characteristics andappearance as well as the good adhesion between the primer layer and thesurface layer.

The ETFE (B) is not particularly restricted but may be any onesatisfying the above-mentioned fluorine content, in particular havingthe fluorine content thereof not lower than that of the ETFE (A). Thus,for example, it may be one obtained by copolymerizing ethylene andtetrafluoroethylene, together with other fluorine-containing monomers,like in the case of the ETFE (A). The other fluorine-containing monomersare as described hereinabove referring to the ETFE (A) and preferablyamount to not more than 5 mole percent of the all monomers in the ETFE(B).

The method of producing the above ETFE (B) is not particularlyrestricted but may be, for example, the same as the method for the ETFE(A), and the fluorine content thereof can be adjusted by the same methodas that for the ETFE (A).

The coating for surface layers is not particularly restricted providedthat it comprises the ETFE (B) having a fluorine content not lower thanthe fluorine content of the ETFE (A), as mentioned above. From renderingthe ETFE-lining member of the present invention excellent not only insurface characteristics, such as corrosion resistance and flameretardancy, but also in appearance characteristics, such ascolorlessness and transparency, however, it is preferred that thecomposition does not contain the binder component mentioned hereinabove.When the binder component is incorporated therein, the ETFE (B) contentin the surface layer lowers and, thus, the surface characteristics maydeteriorate and/or decomposition occurs upon heating in the baking stepto cause discoloration.

The coating for surface layers may contain, in addition to the ETFE (B),other components, such as additive, each in an appropriate amountaccording to need.

The other components are preferably used each in a minimal amount interms of fully making use of the characteristics of the ETFE (B), suchas corrosion resistance. By minimizing the amounts of the othercomponents, it becomes possible to increase the purity of the ETFE (B)in the surface layer, and the surface layer can be inhibited fromadversely affecting water, chemical or other substances coming intocontact therewith in semiconductor manufacturing equipment, chemical ormedical appliances, for instance, and from being deteriorated.

The coating for surface layers may take the form of a water-basedcoating, solvent-based coating or powder coating, for instance. From theenvironmental protection viewpoint, however, a water-based coating andpowder coating are preferred and, from the possibility of increasing thefilm thickness, a powder coating is more preferred.

The powder coating preferably has an average powder particle diameter of10 to 1,000 μm. When that diameter is smaller than 10 μm, electrostaticcoating becomes difficult and, when it exceeds 1,000 μm, the smoothnesstends to become worse at using in the manner of rotolining. The averageparticle diameter of the above powder particles is selected according tothe intended purpose and generally, in the case of a powder coating forforming thin coats which is to give a dry film thickness of not morethan 100 μm, it is preferably 20 to 40 μm and, in the case of a powdercoating for forming thick coats, it is preferably 40 to 80 μm. In thecase of a powder coating for rotolining, it is preferably 200 to 500 μm.

The water-based coating and solvent-based coating mentioned above can beproduced by the same method as mentioned above for the production of theprimer.

The method of producing the above-mentioned powder coating is notparticularly restricted but may be any of the methods known in the art,for instance. Thus, for example, use may be made of the methodcomprising melt-kneading the ETFE (B) and the other component(s)mentioned above according to need, followed by pulverizing, and themethod comprising pulverization and classification in the same manner asdescribed above referring to the method of pulverizing the ETFE (A). Themethod described referring to the ETFE (A) is preferred. The powdercoating can be adjusted to an average particle diameter adequate for themethod of coating application and the film thickness by such a method ofpulverization.

The ETFE-lining member of the present invention comprises the primerlayer and the surface layer laminated on the substrate.

The substrate comprises a metal or a ceramic.

The metal is not particularly restricted but includes, among others,iron; stainless steel such as SUS 304, SUS 316L and SUS 403; aluminum;and plated steel sheets, such as zinc-plated and aluminum-plated steelsheets. The ceramic is not particularly restricted but may be any ofheat-resistant ceramics, including, for example, earthenware, porcelain,alumina materials, zirconia materials, and silicon oxide materials.

The substrate is not particularly restricted but may be any substrategenerally desired to be provided with a lining comprising an ETFE-basedcopolymer. For example, a substrate desired to be provided withcorrosion resistance is preferred. As such substrate, there may bementioned, among others, tanks, vessels, columns, valves, pumps, joints,other piping members, and like members to be provided with acorrosion-resistance lining; chemical or medical appliances, waferbaskets, coil bobbin tower packing materials, valves for chemicals, pumpimpellers, and other members to be provided with corrosion resistance.

If necessary, the substrate may be subjected to such pretreatment ascleaning or surface roughening. Preferably, the substrate is subjectedto such pretreatment as mentioned above in terms of improving theadhesion to the primer layer and preventing the surface layer fromdeteriorating. As the pretreatment, there may be mentioned, for example,the removal of oils from the substrate by using a solvent or cleaningagent or by burning off by baking, for instance; chemical etching byusing hydrochloric acid, sulfuric acid or an alkali, for instance; theoxide removal from the substrate surface or rendering the surface unevenfor an increase in surface area by blast treatment with silica sand, analumina powder or the like. It is also possible to cover the materialwith a ceramic or like material by thermal spraying after blasttreatment and apply the above primer thereto.

The ETFE-lining member of the present invention can be produced byapplying the above-mentioned primer to the above-mentioned substrate anddrying to form a primer layer, applying the coating for surface layersmentioned above to the primer layer, followed by drying if necessary andby baking for the formation of the surface layer.

The method of applying the primer to the substrate is not particularlyrestricted. When the primer is in a liquid form, there may be mentionedsuch a per se known method as spray coating, dipping, or electrostaticcoating. The application can be carried out so that the film thicknessafter drying may preferably amount to 5 to 200 μm. A more preferredlower limit is 10 μm, a more preferred upper limit is 100 μm, and astill more preferred upper limit is 50 μm.

The drying after the above primer application is carried out, forexample, at 80 to 200° C. for 10 to 60 minutes. The above drying may becarried out at room temperature prior to heating and the heatingconditions can be rendered milder.

The method of applying the coating for surface layers is notparticularly restricted. When it occurs as a liquid, for example in thecase of a water-based coating, a solvent-based coating or the like,namely when it occurs as a dispersion, a slurry type one or the like,there may be mentioned the spray coating, roller coating or liketechnique and, in the case of a powder coating, there may be mentionedthe electrostatic spray coating, fluidized bed dipping coating androtolining techniques, among others. The rotolining technique ispreferred as the application method in viewpoint of easily increasingthe film thickness and easily reducing the time of application.

The baking is carried out generally at 260 to 320° C. for 20 to 60minutes although it is not particularly restricted but it may be carriedout at a temperature higher than the melting points, softening points orglass transition points of the above-mentioned ETFE (A) and ETFE (B) atwhich temperature the above-mentioned ETFE (A), ETFE (B), the bindercomponent and the optionally incorporated heat stabilizer will not bedecomposed. When the rotolining technique is employed as the method ofapplying the coating for surface layers, the surface layer formation andbaking are carried out simultaneously.

The surface layer preferably has a film thickness of 100 to 10,000 μmafter the above baking. If the thickness is less than 100 μm, theexcellent characteristics of the corrosion-resistant ETFE (B) is notfully made of use in some cases, in particular in the case ofcorrosion-resistant linings. When it exceeds 10,000 μm, cracking, amongothers, may occur. A more preferred upper limit is 5,000 μm.

The ETFE-lining member of the present invention, in which the primerlayer comprising the binder component and ETFE (A) is laminated betweenthe substrate and the surface layer comprising ETFE (B), is excellent inadhesion between the substrate and primer layer owing to the bindercomponent and shows good interlayer adhesion between the primer layerand the surface layer owing to the compatibility between the ETFE (A)and ETFE (B).

Furthermore, the ETFE-lining member of the present invention, in whichthe fluorine content of the ETFE (B) is not lower than that of the ETFE(A), is firm in interlayer adhesion between the primer layer and thesurface layer. In this manner, the ETFE-lining member of the presentinvention is excellent in adhesion between the substrate and primerlayer and in adhesion between the primer layer and the surface layerand, therefore, no failure in adhesion will occur and such coating filmdefects as blistering and coating film peeling can be reduced.

Therefore, the ETFE-lining member of the present invention can suitablybe used as a corrosion-resistant lining member, for instance. As for thefields of application of such corrosion-resistant lining member, theremay be mentioned, for example, the semiconductor manufacture field,including semiconductor manufacturing apparatus, apparatus for producingchemicals for semiconductor manufacture, and containers for chemicalsfor semiconductor manufacture; the chemical and medical fields,including drug manufacturing apparatus, containers for drugs, chemicalsproducing apparatus, and containers for chemicals; and the foodstufffield, including alcohol fermentation vessels, vessels for brewingfermented foodstuffs, and containers for storing fermented foodstuffs.

BEST MODES FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in more detail.These examples are, however, by no means limitative of the scope of thepresent invention.

PREPARATION EXAMPLE 1

An amount of 30 g of an ETFE powder, namely anethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content50.4% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 10 μm, was used as the ETFE (A), and 10g of a PAI powder, namely a pulverized polyamideimide (PAI, product ofHitachi Chemical) having an average particle diameter of 1.5 μm, wasused as the binder component. They were placed in a stainless steelvessel, together with 0.7 g of a surfactant (trademark: Nonion HS-208;product of NOF Corporation), 0.1 g of dibutylamine and 25 g of purewater. After 20 minutes of stirring at 300 rpm using a propellerstirrer, 20 g of N-2-pyrrolidone was further dispersed therein withstirring to give a primer.

PREPARATION EXAMPLE 2

An amount of 30 g of an ETFE powder, namely anethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content60.4% by mass) having a melt flow rate at 297° C. of 15 g/10 minutes andan average particle diameter of 12 μm, was used as the ETFE (A), and 10g of a PAI powder, namely a pulverized polyamideimide (PAI, product ofHitachi Chemical) having an average particle diameter of 1.5 μm, wasused as the binder component. They were placed in a stainless steelvessel, together with 0.5 g of a surfactant (trademark: Nonion HS-208;product of NOF Corporation), 0.1 g of dibutylamine and 5 g of purewater. After 20 minutes of stirring at 300 rpm using a propellerstirrer, 20 g of N-2-pyrrolidone was further dispersed therein withstirring to give a primer.

PREPARATION EXAMPLE 3

An amount of 30 g of an ETFE, namely anethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 10 μm, was used as the ETFE (A), and 10g of a PAI powder, namely a pulverized polyamideimide (PAI, product ofHitachi Chemical) having an average particle diameter of 1.5 μm, wasused as the binder component. They were placed in a stainless steelvessel, together with 0.7 g of a surfactant (trademark: Nonion HS-208;product of NOF Corporation), 0.1 g of dibutylamine and 25 g of purewater. After 20 minutes of stirring at 300 rpm using a propellerstirrer, 20 g of N-2-pyrrolidone was further dispersed therein withstirring to give a primer.

PREPARATION EXAMPLE 4

A primer was prepared in the same manner as in Preparation Example 2except that 24 g of the ETFE powder and 16 g of the PAI powder wereused.

PREPARATION EXAMPLE 5

A primer was prepared in the same manner as in Preparation Example 1except that a PI powder, namely a pulverized polyimide (PI, product ofHitachi Chemical) having an average particle diameter of 2.5 μm, wasused in lieu of the PAI powder.

PREPARATION EXAMPLE 6

A primer was prepared in the same manner as in Preparation Example 2except that the ETFE powder having an average particle diameter-of 4.8μm was used.

PREPARATION EXAMPLE 7

A primer was prepared in the same manner as in Preparation Example 2except that 15 g of the ETFE powder and 25 g of the PAI powder wereused.

EXAMPLE 1

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 1 was applied to this substrate to a dry film thickness of 30 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content60.4% by mass) having a melt flow rate at 297° C. of 15 g/10 minutes andan average particle diameter of 75 μm was applied as ETFE (B) to a filmthickness after baking of 150 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 550 μm after baking.

EXAMPLE 2

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer, obtained in PreparationExample 2 was applied to this substrate to a dry film thickness of 35 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content60.4% by mass) having a melt flow rate at 297° C. of 15 g/10 minutes andan average particle diameter of 75 μm was applied as ETFE (B) to a filmthickness after baking of 170 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 580 μm after baking.

EXAMPLE 3

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 2 was applied to this substrate to a dry film thickness of 25 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 48 g/10 minutes andan average particle diameter of 73 μm was applied as ETFE (B) to a filmthickness after baking of 200 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 600 μm after baking.

EXAMPLE 4

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 3 was applied to this substrate to a dry film thickness of 30 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 73 μm was applied as ETFE (B) to a filmthickness after baking of 170 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 560 μm after baking.

EXAMPLE 5

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 4 was applied to this substrate to a dry film thickness of 30 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 73 μm was applied as ETFE (B) to a filmthickness after baking of 150 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 550 μm after baking.

EXAMPLE 6

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 5 was applied to this substrate to a dry film thickness of 35 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 73 μm was applied as ETFE (B) to a filmthickness after baking of 150 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 580 μm after baking.

EXAMPLE 7

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 6 was applied to this substrate to a dry film thickness of 35 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content66.6% by mass) having a melt flow rate at 297° C. of 8 g/10 minutes andan average particle diameter of 73 μm was applied as ETFE (B) to a filmthickness after baking of 170 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 560 μm after baking.

COMPARATIVE EXAMPLE 1

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 3 was applied to this substrate to a dry film thickness of 30 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content50.4% by mass) having a melt flow rate at 297° C. of 15 g/10 minutes andan average particle diameter of 75 μm was applied as ETFE (B) to a filmthickness after baking of 150 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 550 μm after baking.

COMPARATIVE EXAMPLE 2

A substrate comprising SUS 304 was degreased using acetone andblast-treated at a pressure of 0.5 MPa using a #60 alumina powder (TosaEmery) in a sandblasting apparatus. The primer obtained in PreparationExample 3 was applied to this substrate to a dry film thickness of 30 μmand, after 15 minutes of drying at 120° C., a powder coating comprisingan ethyene/tetrafluoroethylene/CH₂=CFC₃F₆H copolymer (fluorine content60.4% by mass) having a melt flow rate at 297° C. of 15 g/10 minutes andan average particle diameter of 70 μm was applied as ETFE (B) to a filmthickness after baking of 200 μm, followed by 30 minutes of baking at290° C. Thereafter, the above powder coating was repeatedly appliedthree times in the manner of electrostatic coating. Thus was obtained anETFE-lining member with a film thickness of 590 μm after baking.

Primer Adhesiveness Testing

The coating films of the ETFE-lining members obtained in Examples 1 to 7and Comparative Examples 1 and 2 were each provided with parallelgrooves with a spacing of 10 mm using a knife and subjected to peeltesting at an angle of 90 degrees on an autograph at a speed of 50mm/minute. Separately, the ETFE-lining members obtained were immersed inboiling water at 95° C. for 20 hours or subjected to 72 hours ofannealing in an oven at 200° C. and then subjected to peel testing underthe same conditions. The results are shown in Table 1. TABLE 1 SurfacePrimer layer layer Adhesion strength (kg/cm) ETFE (A) ETFE (B) AfterFluorine Binder ETFE(A)/ Fluorine hot water content component bindercontent treatment After annealing (mass %) species component (mass %)Initial (95° C. × 20 hrs) (200° C. × 72 hrs) Ex. 1 50.4 PAI 75/25 60.414.5 13.8 11.8 Ex. 2 60.4 PAI 75/25 60.4 13.1 12.8 11.6 Ex. 3 60.4 PAI75/25 66.6 15.3 14.5 13.2 Ex. 4 66.6 PAI 75/25 66.6 14.6 14.2 13.3 Ex. 560.4 PAI 60/40 66.6 13.5 13.0 11.2 Ex. 6 50.4 PI 75/25 66.6 12.7 12.112.2 Ex. 7 60.4 PAI 75/25 66.6 15.1 14.3 11.6 Comparative 66.6 PAI 75/2550.4 3.6 1.3 1.3 Ex. 1 Comparative 66.6 PAI 75/25 60.4 6.8 3.1 1.5 Ex. 2

As seen in Table 1, it was found that the adhesion or bond strength isweak in Comparative Examples 1 and 2 in which the fluorine content ofthe ETFE-based copolymer in the powder coating is lower than thefluorine content of the ETFE powder in the primer, whereas the adhesionis excellent in Examples 1 to 7 in which the fluorine content of theETFE-based copolymer is not lower than the fluorine content of the ETFEpowder.

In Table 1, the mass ratios between the ETFE (A) and binder componentare shown. It was found that the adhesion is very strong in Examples 1to 7 in which the ETFE (A) is within the range of 50 to 90% of the sumof the ETFE (A) and binder component on the solid matter mass basis.

INDUSTRIAL APPLICABILITY

The ETFE-lining member of the present invention, which has theconstitution described hereinabove, is excellent in adhesion between thesubstrate and primer layer and in adhesion between the primer layer andthe surface layer and, thus, can be obtained as one with a reducedcoating film defects.

1. An ETFE-lining member comprising a substrate, a primer layer and asurface layer laminated in this order, wherein said substrate comprisesa metal or a ceramic, said primer layer comprises an ETFE (A) and abinder component, and said surface layer comprises an ETFE (B) havingfluorine content not lower than that of said ETFE (A).
 2. TheETFE-lining member according to claim 1, wherein the ETFE (A) amounts to50 to 90% of the sum of the ETFE (A) and the binder component on thesolid matter mass basis and said ETFE (A) has a fluorine content of notlower than 50% by mass.
 3. The ETFE-lining member according to claim 1,wherein the ETFE (A) has a melt flow rate of 0.1 to 100 g/10 minutes. 4.The ETFE-lining member according to claim 1, wherein the bindercomponent is a polyamideimide resin, a polyethersulfone and/or apolyimide resin.
 5. The ETFE-lining member according to claim 1, whereinthe ETFE (B) has a fluorine content of 50 to 70% by mass.